Although the most common measure of global warming is the increase in the near-surface atmospheric temperature, over 90% of the additional energy stored in the climate system over the last 50 years has warmed ocean water.
Global warming refers to global averages, with the amount of warming varying by region.
Because the climate system has large thermal inertia, it can take centuries for the climate to fully adjust.
While record-breaking years attract considerable public interest, individual years are less significant than the overall trend.
The largest human influence has been the emission of greenhouse gases such as carbon dioxide, methane, and nitrous oxide.
Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to 1.7 °C (0.5 to 3.1 °F) in a moderate scenario, or as much as 2.6 to 4.8 °C (4.7 to 8.6 °F) in an extreme scenario, depending on the rate of future greenhouse gas emissions and on climate feedback effects.For other uses see Global warming (disambiguation).Global mean surface temperature from 1880 to 2018, relative to the 1951–1980 mean.The Northern Hemisphere and North Pole have warmed much faster than the South Pole and Southern Hemisphere.The Northern Hemisphere not only has much more land, but the arrangement of land masses around the Arctic Ocean has resulted in the maximum surface area flipping from reflective snow and ice cover to ocean and land surfaces that absorb more sunlight and thus more heat.Because the climate system has a large "inertia" and greenhouse gases persist in the atmosphere, climatic changes and their effects will continue for many centuries even if greenhouse gas emissions are stopped.Possible societal responses to global warming include mitigation by emissions reduction, adaptation to its effects, and maybe climate engineering.The black line is the global annual mean, and the red line is the five-year local regression line. Global warming is the long-term rise in the average temperature of the Earth's climate system.It is a major aspect of current climate change, and has been demonstrated by direct temperature measurements and by measurements of various effects of the warming.Global surface temperature is subject to short-term fluctuations that overlie long-term trends, and can temporarily mask or magnify them.Throughout this period ocean heat storage continued to progress steadily upwards, and in subsequent years surface temperatures have spiked upwards.